Dramatically Enhanced Ambient Ammonia Electrosynthesis Performance by In-Operando Created Li-S Interactions on MoS2 Electrocatalyst

The Haber-Bosch process can be replaced by the ambient electrocatalytic N-2 reduction reaction (NRR) to produce NH3 if suitable electrocatalysts can be developed. However, to develop high performance N-2 fixation electrocatalysts, a key issue to be resolved is to achieve efficient hydrogenation of N-2 without interference by the thermodynamically favored hydrogen evolution reaction (HER). Herein, in-operando created strong Li-S interactions are reported to empower the S-rich MoS2 nanosheets with superior NRR catalytic activity and HER suppression ability. The Li+ interactions with S-edge sites of MoS2 can effectively suppress hydrogen evolution reaction by reducing H* adsorption free energy from 0.03 to 0.47 eV, facilitate N-2 adsorption by increasing N-2 adsorption free energy from -0.32 to -0.70 eV and enhance electrocatalytic N-2 reduction activity by decreasing the activation energy barrier of the reaction control step (*N-2 *N2H) from 0.84 to 0.42 eV. A NH3 yield rate of 43.4 g h(-1) mg(-1) MoS2 with a faradaic efficiency (FE) of 9.81% can be achieved in presence of strong Li-S interactions, more than 8 and 18 times by the same electrocatalyst in the absence of Li-S interactions. This report opens a new way to design and develop catalysts and catalysis systems.